<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      div {
        width: 800px;
        height: 500px;
        background-color: pink;
        /* flex 布局 */
        display: flex;
        justify-content: center;
        /* 设置侧轴上子元素的排列方式 */
        /* flex-start, flex-end, center, stretch */
        align-items: center;
      }
      div span {
        width: 200px;
        height: 100px;
        background-color: purple;
        margin: 10px;
      }
    </style>
  </head>
  <body>
    <div><span>1</span><span>2</span><span>3</span></div>
  </body>
</html>
